Spam despite captcha?

I have captcha set up on this form but they are still claiming to be receiving an abundant amount of spam.
Any ideas? Please help.

http://www.pacsswitchgearllc.com/index.php/contact-us

Hi infolink,

The Captcha appears to be working correctly so I suggest that you add some serverside validation to block the worst of the spam messages. Usually there is some visible pattern to the spam that can be used - IP Addresses, email, URLs in text, . . .

Bob

I will look into that. Thank you.